Cox, an Army veteran, says the trooper wouldn't let him properly record the stop with his cell phone. He posted about the stop online on the Virginia Copblock website. The cell phone and police dash camera video went viral.

Now, Trooper McKenney has filed suit against Cox for defamation.

During the incident, Cox says Trooper McKenney approached his car and immediately asked him to step out.

"I'm asking you to step out because if you have something in there," McKenney can be heard saying to Cox in the video.

"No ma'am, you're not taking my phone," replied Cox.

Cox says was trying to record the stop on his cell phone, which is legal if it doesn't interfere with an officer's work.

"There are two competing interests here," said Benjamin. "One is our right to be protected against false statements that truly injure us, but on the other hand this is a free country. One thing we value above all else is the right to speak freely, even though sometimes that speech can be very, very hurtful."

An important point about defamation lawsuits is that truth is an absolute defense. If a judge finds that Cox's accusations are justified, Trooper McKenney could lose the case.

State police say Trooper McKenney is declining comment.

NBC12 spoke to the executive director of the Virginia Association of Chiefs of Police, Dana Schrad.

"The irony for officers is that they see themselves as public servants and there to help and protect and serve the public. And yet, they often get treated with a lot of derision, so that can be stressful. That can be demoralizing," said Schrad.